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Wednesday, October 7, 2015

Should veterinarians advise human patients about zoonoses?

Humans and animals can share diseases. Should they share doctors?

Should veterinarians play a formal role in advising human
patients about zoonotic diseases? It’s an interesting question, addressed in a
fascinating paper by Emeritus Professor Rick Speare and colleagues. Professor Speare is a veterinarian
and medical doctor, and has worked with humans and non-human patients, so he
has a fairly unique perspective. He’s also committed to ensuring that “OneHealth”
isn’t just a buzzword.

Zoonotic diseases are those acquired by humans from
non-human animals (for example, rabies may be transmitted from animals to
humans in some circumstances, and dog bites remain a major source of rabies
transmission in endemic countries). Humanoses are those diseases acquired by
animals from human sources (for example, H1N1 influenza was spread from humans
to pigs and poultry; Mycobacterium
tuberculosis has been transmitted from humans to cattle). Some diseases
travel both ways, so they’re both.

The argument the authors make in this paper is
interesting. Previous surveys have established that, in general, doctors feel
that vets know more about zoonoses – perhaps more in terms of how to reduce the
risk of being exposed to the bugs that cause them and less about their
treatment in human patients.

However, in the main – aside from a few exceptions (and
they are around, for example a number of prominent veterinarians are involved
with the Australasian Society for Infectious Diseases) – doctors don’t talk to
vets and vets don’t talk to doctors.

“The outcome is that the profession thought to be the
most expert on zoonoses is not involved in the management of individual patients.”

The paper does not suggest that vets open our doors to
non-human patients and start treating them (not that we don’t get the odd
request, which is always politely redirected). But it does suggest that
veterinary expertise could help in a number of ways:

Vets could provide accurate, comprehensive information
about the epidemiology of the disease a patient has, which may be useful in
differentiating between human, animal or environmental sources of a disease
(for example, ringworm in a patient);

Vets could help evaluate specific risk factors for
zoonotic disease exposure – for example advising animal caretakers how to
decrease risks of infection of their animal with zoonotic diseases (for
example, there has been a spike in cases of Brucella
suis in pig hunters and their dogs in Northern New South Wales this year);

Vets could advice on the management of affected animals,
including vaccination strategies (for example, for leptospirosis in a dairy
herd);

Vets could provide advice to patients at increased risk
of zoonotic disease or at increased risk of catastrophic effects from zoonoses –
for example, people undergoing immunosuppressive treatment, those with an
immunodeficiency disorder, or pregnant women.

If vets and doctors worked together, it would be much
easier to determine in the source of the infection or reinfection is the
animal, the environment or human. The way I read the article was that the
doctor would still be in charge of treating the human in the equation, but the
veterinarian involved would treat (if required) affected animals and ensure
that risks of further exposure or reinfection are minimised.

Professor Speare and colleagues analysed survey data and found
that, in Queensland at least, the majority (79.8 per cent) of respondents would
be willing to seek advice from a vet about zoonotic disease if their doctor
recommended it. That proportion climbed to 90.7 per cent if the bill was funded
by Medicare.

Is this a case of vets trying to encroach on medical
turf? Not at all. Doctors in Australia refer to a range of allied health
professionals and Medicare provides rebates if patients are referred to
eligible providers (for example, dieticians, physiotherapists, speech
pathologists, psychologists, osteopaths and so forth).

The authors argue that, just as these allied health
professions have expertise in their areas, “Veterinarians have multi-species
training and experience and are more familiar than physicians in considering
management strategies involving more than one species.”

Not all of my colleagues agree that this argument is
compelling. Some feel that many veterinarians do not have the level of
expertise and training around human patients that would be required. One
colleague argued vehemently that a good infectious disease physician knows more
than any vet OR doctor about zoonoses.

Certainly if such a model were adopted, and one could be
referred to a veterinarian as PART of the management of a zoonotic disease,
additional training of a select group of veterinarians would be required. Perhaps
these veterinarians should undertake postgraduate training in public health (as
many already do) or maybe they should be specialists.

Personally I think this is an idea worth exploring. As a
veterinarian I am often asked for advice by clients about zoonoses in general,
often because they have been misinformed. For example, I have counselled pet
owners who have been advised to euthanase their cat if they are pregnant due to
what their doctor believes is an unacceptably increased risk of catastrophic
consequences from infection with Toxoplasma
gondii during pregnancy. Often the doctor involved does not realise that people are more
likely to acquire the infection from other sources (unwashed fruit and
vegetables, undercooked meat) and that the risks of feline transmission can be minimised by simple hand and litter tray hygiene.

I do give general advice about reducing risk of exposure
when animals have an infection (for example, a kitten or puppy with ringworm).
I always, always recommend that humans consult a doctor about medical issues
that may affect them. But it would be helpful to establish a more formal path
of communication between veterinarians and doctors.

Veterinary Ethics: Navigating Tough Cases

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